Hi Philip, I will monitor it till tomorrow. Just connected my laptop instead of probe, and ran udp test ping with different ttl. Test were successful, traffic passes the firewall. Probe still rebooting. C:\Program Files\Nmap>nping.exe --udp --ttl 3 -g 54767 8.8.8.8 Starting Nping 0.5.51 ( http://nmap.org/nping ) at 2012-11-05 17:54 E. Europe Standard Time SENT (0.6090s) UDP 10.20.30.6:54767 > 8.8.8.8:40125 ttl=3 id=19712 iplen=28 RCVD (0.7960s) ICMP 10.251.0.113 > 10.20.30.6 TTL=0 during transit (type=11/code=0) ttl=253 id=30800 iplen=56 SENT (1.7810s) UDP 10.20.30.6:54767 > 8.8.8.8:40125 ttl=3 id=19712 iplen=28 RCVD (1.7810s) ICMP 10.251.0.113 > 10.20.30.6 TTL=0 during transit (type=11/code=0) ttl=253 id=30801 iplen=56 SENT (2.7810s) UDP 10.20.30.6:54767 > 8.8.8.8:40125 ttl=3 id=19712 iplen=28 RCVD (2.7810s) ICMP 10.251.0.113 > 10.20.30.6 TTL=0 during transit (type=11/code=0) ttl=253 id=30802 iplen=56 SENT (3.7810s) UDP 10.20.30.6:54767 > 8.8.8.8:40125 ttl=3 id=19712 iplen=28 RCVD (3.7810s) ICMP 10.251.0.113 > 10.20.30.6 TTL=0 during transit (type=11/code=0) ttl=253 id=30803 iplen=56 SENT (4.7810s) UDP 10.20.30.6:54767 > 8.8.8.8:40125 ttl=3 id=19712 iplen=28 RCVD (4.7810s) ICMP 10.251.0.113 > 10.20.30.6 TTL=0 during transit (type=11/code=0) ttl=253 id=30804 iplen=56 Max rtt: 15.000ms | Min rtt: 0.000ms | Avg rtt: 3.000ms Raw packets sent: 5 (210B) | Rcvd: 5 (280B) | Lost: 0 (0.00%) Tx time: 4.17200s | Tx bytes/s: 50.34 | Tx pkts/s: 1.20 Rx time: 5.17200s | Rx bytes/s: 54.14 | Rx pkts/s: 0.97 Nping done: 1 IP address pinged in 5.78 seconds